Crosslinking compounds based on furocoumarin (or psoralen) are disclosed in U.S. Pat. No. 4,826,967 to Glass. The compounds are attached to existing polynucleotides, usually through adduct formation. Psoralen is fluorescent with emission in the range of 450-500 nm with a low quantum yield of less than 10−2 in the uncrosslinked state. The crosslinked psoralen photoproduct, however, has greatly reduced fluorescence. See “Bioorganic Photochemistry: Photochemistry of the Nucleic Acids,” Vol. 1, Morrison, H., ed., Wiley and Sons, New York, 1990.
U.S. Pat. No. 5,082,934 to Saba et al. discloses a nucleoside analogue comprising a coumarin moiety linked through its phenyl ring to the 1-position of a ribose or deoxyribose sugar moiety in the absence of an intervening base moiety. The resulting nucleoside analogue is used as a crosslinking group when inserted into a polynucleotide as a replacement for one or more of the complementary nucleoside bases present in a probe used in hybridization assays. The sugar moiety, however, limits the conformational flexibility of the crosslinking group.
PCT Publication Number WO96/28438 to Wood et al. discloses non-nucleosidic coumarin derivatives wherein the coumarin moiety is joined within the backbone of an oligonucleotide probe via moieties other than deoxyribose or ribose.
Additionally, U.S. Pat. No. 6,303,799 to Cheng et al. discloses aryl olefins as crosslinking groups in oligonucleotide probes for use in hybridization-based assays and as therapeutic agents.
With the ever-increasing use of oligonucleotide probe technology in biological and medical research, there remains a need for additional cross-linking probes. In particular, there is an outstanding need for additional cross-linking probes that would facilitate the detection of the cross-linked products or photoproducts of the probes and their nucleic acid targets. Such probes could have application in cellular assays to determine the genotype or presence of an infectious agent and in oligonucleotide arrays for the quantification of oligonucleotides in a sample obtained from a living cell.